In recent years, the industry of novel Flat Panel Display (FPD) has been developed dramatically, and a high demand of consumers for large-size and high resolution FPD is urging the whole industry to improve display technologies constantly. As a core technology of the PFD industry, the Thin Film Transistor (TFT) backplane technology is also experiencing a profound reform.
Because of a relatively low mobility (generally smaller than 0.5 cm2/(V·s)), traditional amorphous silicon (a-Si) can hardly implement high definition display, and is facing the fate of being eliminated by the market. Although having a high mobility (50 to 150 cm2/(V·s)), a Low Temperature Polycrystalline Silicon (LTPS) TFT is complicated in production techniques and expensive in equipment investment on one hand, and has problems including poor uniformity and low rate of good products in large-size display on the other hand, thereby resulting in difficult further development of LTPS in the field of large size FPD. In contrast, an MOTFT not only has a relatively high mobility (about 5 to 50 cm2/(V·s)), but also is prepared with simple techniques and low manufacture cost, and has excellent uniformity in a large area. Therefore, the MOTFT technology has attracted great attention in the industry since its emergence.
At present, an MOTFT mainly uses a back channel etch structure and an etch barrier layer structure. The back channel etch structure is formed by depositing a metal layer and patterning the metal layer as a source electrode and a drain electrode on an active layer after the active layer is generated while the etch barrier layer structure is formed by depositing a metal layer and patterning the metal layer as a source electrode and a drain electrode on an etch barrier layer which is manufactured first after an active layer is generated.
The back channel etch structure is manufactured with a relatively simple technique, and what is the same as a traditional a-Si manufacture technique is that the equipment investment and production cost are relatively low. The structure is believed to be an inevitable development direction of mass production and wide application of MOTFTs. However, a back channel may be damaged no matter dry etching or wet etching is applied when the source electrode and the drain electrode are etched on the active layer: when drying etching is applied, a metal oxide is easily damaged by ions, which generates a carrier bulk trap on the exposed channel surface and increases the oxygen vacancy concentration to lower the device stability; when the wet etching is applied, the active layer, which is sensitive to most acid etchants, is easily etched during an etching process, thereby greatly affecting the device performance. Currently, an MOTFT having the structure can be hardly productized.
An MOTFT using the etch barrier layer structure can avoid the foregoing problem to a large extent, thus the MOTFT is more stable. A TFT using the structure has been commercialized at present. However, the TFT requires an additional photoetching mask to manufacture the etch barrier layer, which results in complicated techniques and high manufacture cost.
Therefore, it is necessary to provide an MOTFT with good stability, simple preparation techniques and low cost and a preparation process thereof so as to overcome disadvantages of the prior art.